Neurochemical anatomy of dorsal and tonic immobility responses

Tonic immobility and phenomenal consciousness in animals: a review

Tonic immobility (TI) is an innate, last-resort response to the presence of a predator, commonly referred to as feigning death or thanatosis. However, it is critical to distinguish death feigning from TI; the former encompasses a complex series of behaviors, with TI representing its final aspect. Given this complexity, death feigning is hypothesized to manifest a higher-order intentionality in animals. Considering that third-order and higher intentional states are correlated with some form of phenomenal consciousness, their presence in animals has significant implications for their conscious experiences. This hypothesis surrounding third-order and higher intentional states is subject to dispute, in part due to the lack of sufficient evidence indicating that the behaviors associated with death feigning, aside from TI, serve a protective function against predation. Evidence suggests that TI alone constitutes an effective mechanism for predator defense. It is posited that the cessation of TI by the prey organism signifies the presence of a first-order intentional state. Furthermore, it is proposed that behavioral indicators suggest that the termination of TI by the prey is linked to anoetic and potentially noetic consciousness. The relationship between TI and fear is also examined. It is contended that, within the framework of formulating hypotheses concerning the mechanisms of TI and developing experimental designs to test these hypotheses, fear should be characterized as an intervening variable. The conclusions derived from this analysis indicate that TI can occasionally function as an effective predator defense associated with primal sensory and anoetic consciousness. Its termination may imply the presence of noetic consciousness; however, self-reflective autonoetic consciousness appears to be absent. Finally, the hypothesis suggesting that TI serves as an evolutionary precursor to the theory of mind in humans is discussed, serving as a cautionary note in the interpretation of findings from animal research concerning the evolution of cognitive functions in humans.

Tactile mechanisms and afferents underlying the rat pup transport response

Juvenile rodents and other altricial mammals react with calming, immobility, and postural modifications to parental pickup, a set of behaviors referred to as the transport response.1,2,3,4,5 Here, we investigate sensory mechanisms underlying the rat transport response. Grasping rat pups in anterior neck positions evokes strong immobility and folding up of feet, whereas more posterior grasping has lesser effects on immobility and foot position. Transport responses are enhanced by slow (1 Hz), and even more so by fast (4 Hz), gentle shaking and translation, features consistent with parental transport. With lateral grasping, the forepaw below the grasping position points downward and the forepaw lateral to the grasping position points upward and medially. Such forepaw adjustments put the pup's center of gravity below the grasping point, optimizing pup transportability. Tactile stimuli on the back, belly, tail, whisker, dorsal forepaws, and dorsal hind-paws do not significantly affect behavior of anterior-neck-held pups. Instead, ground contact, or paw stimulation consistent with ground contact, disrupts transport responses. We identify afferents mediating transport response by examining membrane labeling with FM 1-436 following anterior neck grasping. We observe a dense innervation of the anterior-neck-skin region (∼30 terminals/mm2). We find an age-related decrease of cytochrome oxidase reactivity in the rat somatosensory cortical neck representation, a possible correlate to developmental decrease in pup transport response. We conclude that anterior neck grasping and loss of ground contact trigger calming and postural adjustments for parental transport in rat pups, responses putatively driven from the densely innervated anterior neck skin.

Enhancing Conceptual Clarity regarding the Construct of Moral Injury

BACKGROUND

The construct of "moral injury" is used widely in the research literature and media to broadly describe the impact of events involving perceived violations of one's sense of right and wrong (herein referred to as "potentially morally injurious events" [PMIEs]).

SUMMARY

In this theoretical review, we provided a brief overview of the "moral injury" construct and its limitations including the lack of consensus-drawn boundaries and operational definitions to guide hypothesis-driven research. We discussed whether this construct can be reliably distinguished from established psychiatric diagnoses and psychological constructs and the inherent challenges in separating or classifying the impact of high-magnitude stressful life events that likely form the majority of PMIEs. Assessments that purportedly measure "moral injury" are reviewed and limitations are discussed such as shared measurement variance with established psychological instruments.

KEY MESSAGES

We identified conceptual strategies for investigating behavioral and neurobiological features of PMIEs that could be used to inform the field of traumatic stress. We concluded that the construct of "moral injury" may provide an interpretive framework for positing why someone may be beset by guilt, shame, and/or rage whereas existing psychiatric diagnoses such as post-traumatic stress disorder and depression provide comprehensive descriptions regarding what someone might experience following extremely stressful events. We proposed directions to better clarify the boundaries of "moral injury" versus established psychiatric categories that could be used to enhance the conceptualization and assessment of this construct.

Non-angry aggressive arousal and angriffsberietschaft: A narrative review of the phenomenology and physiology of proactive/offensive aggression motivation and escalation in people and other animals

Human aggression typologies largely correspond with those for other animals. While there may be no non-human equivalent of angry reactive aggression, we propose that human proactive aggression is similar to offense in other animals' dominance contests for territory or social status. Like predation/hunting, but unlike defense, offense and proactive aggression are positively reinforcing, involving dopamine release in accumbens. The drive these motivational states provide must suffice to overcome fear associated with initiating risky fights. We term the neural activity motivating proactive aggression "non-angry aggressive arousal", but use "angriffsberietschaft" for offense motivation in other animals to acknowledge possible differences. Temporal variation in angriffsberietschaft partitions fights into bouts; engendering reduced anti-predator vigilance, redirected aggression and motivational over-ride. Increased aggressive arousal drives threat-to-attack transitions, as in verbal-to-physical escalation and beyond that, into hyper-aggression. Proactive aggression and offense involve related neural activity states. Cingulate, insular and prefrontal cortices energize/modulate aggression through a subcortical core containing subnuclei for each aggression type. These proposals will deepen understanding of aggression across taxa, guiding prevention/intervention for human violence.